1. Technical Field
The present invention relates to a piezoelectric element that has a piezoelectric material layer interposed between electrode layers that make a pair. The invention also relates to a liquid ejecting head and a liquid ejecting apparatus that use the piezoelectric element.
2. Related Art
Liquid ejecting apparatuses are equipped with liquid ejecting heads, and eject various types of liquid from the liquid ejecting head. Such liquid ejecting apparatuses include, for example, image recording apparatuses, such as, ink jet type printers, ink jet type plotters, etc., and have also recently been applied to various kinds of production apparatuses by making use of the apparatuses' feature of being capable of accurately depositing very small amounts of liquid at predetermined positions. Examples of use of liquid ejecting apparatuses in production apparatuses include a display production apparatus for producing a color filter for a liquid crystal display or the like, an electrode forming apparatus for forming electrodes of an organic electro-luminescence (EL) display, a surface emitting display (SED), etc., and a chip production apparatus for producing a bio-chip (biochemical device). While a recording head for an image recording apparatus ejects liquid inks, a color material ejecting head for a display production apparatus ejects solutions of color materials of red (R), green (G) and blue (B). Furthermore, an electrode material ejecting head for an electrode forming apparatus ejects an electrode material in a liquid state, and a bioorganic material ejecting head for a chip production apparatus ejects a solution of a bioorganic material.
The aforementioned liquid ejecting heads each include piezoelectric elements that cause pressure changes in liquid within pressure chambers. Such a piezoelectric element is made up of, for example, a lower electrode layer that functions as an individual electrode provided for each of pressure chambers, a piezoelectric material layer of lead zirconate titanate (also termed PZT) or the like, an upper electrode layer that functions as a common electrode that is common to a plurality of pressure chambers which are formed and layered in that order from a side nearer to the pressure chamber by a film forming technology. A portion of the piezoelectric material layer disposed between the upper electrode layer and a lower electrode layer is an active portion that deforms when voltage is applied to the two electrode layers. Note that when the piezoelectric element deforms, stress may concentrate at a boundary location between the active portion and a portion that is not the active portion (non-active portion), leading to formation of cracks in the piezoelectric material layer that constitutes the piezoelectric element. Therefore, a technology in which a piezoelectric material layer and an upper electrode layer are formed so as to extend into an outer side of the pressure chamber in the longitudinal direction so that the rigidity of the aforementioned boundary location in the piezoelectric element is increased (see, e.g., JP-A-2013-158909) has been disclosed.
However, there are cases where the adoption of the foregoing construction does not sufficiently inhibit occurrence of a defective condition in which cracks are formed in the piezoelectric material layer.